Capital Stock - Net Income Per Common Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Income (loss) from continuing operations									$ (4,886)	$ 2,380	$ 1,911
Income (loss) from discontinued operations									(517)	(192)	14
Net income (loss) attributable to common shareholders	(4,814)	(1,330)	505	236	174	300	1,016	698	(5,403)	2,188	1,925
Mandatory Convertible Preferred Stock										44	76
Income (loss) from continuing operations									(4,886)	2,424	1,911
Income (loss) from discontinued operations									(517)	(192)	14
Net income (loss) attributable to common stock									$ (5,403)	$ 2,232	$ 1,925
Income (loss) from continuing operations, shares									384	395	389
Income (loss) from discontinued operations, shares									384	395	389
Net income (loss) attributable to common stock, shares									384	395	389
Mandatory Convertible Preferred Stock, shares										9
Stock options and other, shares										2	2
Income (loss) from continuing operations, shares									384	406	391
Income (loss) from discontinued operations, shares									384	406	391
Net income (loss) attributable to common stock, shares									384	406	391
Basic income (loss) from continuing operations per share	$ (12.78)	$ (3.50)	$ 1.31	$ 1.92	$ 0.43	$ 1.08	$ 2.60	$ 1.94	$ (12.72)	$ 6.02	$ 4.91
Basic income (loss) from discontinued operations per share				$ (1.32)	$ 0.01	$ (0.33)	$ (0.01)	$ (0.16)	$ (1.34)	$ (0.49)	$ 0.04
Net income (loss) attributable to common stock, per share	$ (12.78)	$ (3.50)	$ 1.31	$ 0.60	$ 0.44	$ 0.75	$ 2.59	$ 1.78	$ (14.06)	$ 5.53	$ 4.95
Diluted income (loss) from continuing operations per share	$ (12.78)	$ (3.50)	$ 1.31	$ 1.90	$ 0.43	$ 1.07	$ 2.54	$ 1.91	$ (12.72)	$ 5.97	$ 4.89
Diluted income (loss) from discontinued operations per share				$ (1.30)		$ (0.32)		$ (0.15)	$ (1.34)	$ (0.47)	$ 0.03
Net income (loss) attributable to common stock, per share	$ (12.78)	$ (3.50)	$ 1.31	$ 0.60	$ 0.43	$ 0.75	$ 2.54	$ 1.76	$ (14.06)	$ 5.50	$ 4.92